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Mathot KJ, Arteaga-Torres JD, Besson A, Hawkshaw DM, Klappstein N, McKinnon RA, Sridharan S, Nakagawa S. A systematic review and meta-analysis of unimodal and multimodal predation risk assessment in birds. Nat Commun 2024; 15:4240. [PMID: 38762491 PMCID: PMC11102462 DOI: 10.1038/s41467-024-48702-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 05/07/2024] [Indexed: 05/20/2024] Open
Abstract
Despite a wealth of studies documenting prey responses to perceived predation risk, researchers have only recently begun to consider how prey integrate information from multiple cues in their assessment of risk. We conduct a systematic review and meta-analysis of studies that experimentally manipulated perceived predation risk in birds and evaluate support for three alternative models of cue integration: redundancy/equivalence, enhancement, and antagonism. One key insight from our analysis is that the current theory, generally applied to study cue integration in animals, is incomplete. These theories specify the effects of increasing information level on mean, but not variance, in responses. In contrast, we show that providing multiple complementary cues of predation risk simultaneously does not affect mean response. Instead, as information richness increases, populations appear to assess risk more accurately, resulting in lower among-population variance in response to manipulations of perceived predation risk. We show that this may arise via a statistical process called maximum-likelihood estimation (MLE) integration. Our meta-analysis illustrates how explicit consideration of variance in responses can yield important biological insights.
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Affiliation(s)
- Kimberley J Mathot
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.
- Canada Research Chair in Integrative Ecology, Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.
| | | | - Anne Besson
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
- Department of Zoology, University of Otago, Otago, New Zealand
| | - Deborah M Hawkshaw
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Natasha Klappstein
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
- Department of Statistics, Dalhousie University, Halifax, NS, Canada
| | - Rebekah A McKinnon
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Sheeraja Sridharan
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Shinichi Nakagawa
- Evolution & Ecology Research Centre and School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
- Theoretical Sciences Visiting Program, Okinawa Institute of Science and Technology Graduate University, Okinawa, Onna, 904-0495, Japan
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Fear of predators in free-living wildlife reduces population growth over generations. Proc Natl Acad Sci U S A 2022; 119:2112404119. [PMID: 35131939 PMCID: PMC8851447 DOI: 10.1073/pnas.2112404119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/13/2021] [Indexed: 11/22/2022] Open
Abstract
Accurately evaluating the total impact of predators on prey population growth rates is fundamental to forecasting the consequences of predator conservation and management. That the fear (antipredator responses) predators inspire could contribute to this total impact has only relatively recently been recognized. We experimentally demonstrate that fear itself can impact prey population growth rates in free-living wildlife, extending to transgenerational impacts reducing population growth beyond the parental generation. We report how fear may contribute considerably to the total impact of predators and why this may be the norm in birds and mammals. The critical significance of our work lies in experimentally establishing that inferring the effects of predators using data on direct killing alone risks dramatically underestimating their total impact. Correctly assessing the total impact of predators on prey population growth rates (lambda, λ) is critical to comprehending the importance of predators in species conservation and wildlife management. Experiments over the past decade have demonstrated that the fear (antipredator responses) predators inspire can affect prey fecundity and early offspring survival in free-living wildlife, but recent reviews have highlighted the absence of evidence experimentally linking such effects to significant impacts on prey population growth. We experimentally manipulated fear in free-living wild songbird populations over three annual breeding seasons by intermittently broadcasting playbacks of either predator or nonpredator vocalizations and comprehensively quantified the effects on all the components of population growth, together with evidence of a transgenerational impact on offspring survival as adults. Fear itself significantly reduced the population growth rate (predator playback mean λ = 0.91, 95% CI = 0.80 to 1.04; nonpredator mean λ = 1.06, 95% CI = 0.96 to 1.16) by causing cumulative, compounding adverse effects on fecundity and every component of offspring survival, resulting in predator playback parents producing 53% fewer recruits to the adult breeding population. Fear itself was consequently projected to halve the population size in just 5 years, or just 4 years when the evidence of a transgenerational impact was additionally considered (λ = 0.85). Our results not only demonstrate that fear itself can significantly impact prey population growth rates in free-living wildlife, comparing them with those from hundreds of predator manipulation experiments indicates that fear may constitute a very considerable part of the total impact of predators.
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Lowe WH, Martin TE, Skelly DK, Woods HA. Metamorphosis in an Era of Increasing Climate Variability. Trends Ecol Evol 2021; 36:360-375. [PMID: 33414021 DOI: 10.1016/j.tree.2020.11.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 11/20/2020] [Accepted: 11/30/2020] [Indexed: 12/11/2022]
Abstract
Most animals have complex life cycles including metamorphosis or other discrete life stage transitions, during which individuals may be particularly vulnerable to environmental stressors. With climate change, individuals will be exposed to increasing thermal and hydrologic variability during metamorphosis, which may affect survival and performance through physiological, behavioral, and ecological mechanisms. Furthermore, because metamorphosis entails changes in traits and vital rates, it is likely to play an important role in how populations respond to increasing climate variability. To identify mechanisms underlying population responses and associated trait and life history evolution, we need new approaches to estimating changes in individual traits and performance throughout metamorphosis, and we need to integrate metamorphosis as an explicit life stage in analytical models.
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Affiliation(s)
- Winsor H Lowe
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA.
| | - Thomas E Martin
- US Geological Survey, Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT 59812, USA
| | - David K Skelly
- School of the Environment, Yale University, New Haven, CT 06520, USA
| | - H Arthur Woods
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
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